Digital gas mass flow controllers

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This proposal is requesting funding to purchase gas flow controllers which are instruments that allow for the precise regulation of the amount of gas (oxygen, carbon dioxide and nitrogen) that flows into an experimental set-up. These controllers are connected to tanks of compressed gases which provide the controller with an inflow of gas. The inflow of gas is regulated in terms of the pressure delivered to the controller but not in terms of the actual quantity or volume of gas. The controller is then set such that the outflow of gas from the controller is tightly and accurately regulated in terms of the volume of out-flowing gas per minute. The research that this equipment will support examines mechanisms involved in controlling breathing in amphibians. Amphibian breathing is interesting and important because, unlike humans and other mammals, amphibians do not breathe continuously. Rather, they display a discontinuous pattern of breathing called episodic breathing. This type of breathing involves the grouping of 4-8 breaths into discrete episodes separated by periods of no breathing called apneas (which can be several minutes in length). While episodic breathing is normal in amphibians, it is abnormal and pathological in humans. Humans can display this pattern of breathing during sleep either due to an obstruction of the airway (obstructive sleep apnoea) or due to abnormalities in the areas of the brain that regulate continuous breathing (central sleep apnoea). Apnoea in humans is associated with increased risk for cardiovascular disease such as heart attack or stroke. This research will examine the mechanisms within the amphibian brain that lead to the production of episodic breathing and may lead to insight into brain-related breathing disorders in humans. To do this, we experimentally manipulate neurochemical systems in various regions of the brain (by injecting various drugs) and observe how breathing changes. Since different levels of oxygen and carbon dioxide can alter breathing on their own (without manipulating brain neurochemicals) it is essential that we control the gas levels in an experiment using the gas flow controllers.